* `sub $mDst0, $mSrc1, $mSrc0`
* `sub $mDst0, zimm16, $mSrc0`
* `sub $mDst0, simm16, $mSrc0`

Integer subtraction of 1 register value from another or from immediate.
Immediates may be *sign extended*, *zero extended* or *zero tailed* to
*word* width.